Commit 5a8638d6 authored by Lu Jialin's avatar Lu Jialin Committed by Ma Wupeng
Browse files

cgroup: Add cgroup1_get_from_id() 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5ZG61



-------------------------------

Add cgroup1_get_from_id() function to help cgroupv1 get cgroup through
cgroup inode;

The patch also export cgroup_tryget_css(), which will be used later

Signed-off-by: default avatarLu Jialin <lujialin4@huawei.com>
parent 1b709179

include/linux/cgroup-defs.h

+2 −0
Original line number Diff line number Diff line
@@ -790,6 +790,8 @@ static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) 
	percpu_up_read(&cgroup_threadgroup_rwsem);

}



struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,

					      struct cgroup_subsys *ss);

#else	/* CONFIG_CGROUPS */



#define CGROUP_SUBSYS_COUNT 0

include/linux/cgroup.h

+1 −0
Original line number Diff line number Diff line
@@ -696,6 +696,7 @@ static inline void cgroup_kthread_ready(void) 
}



void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen);

struct cgroup *cgroup1_get_from_id(struct cgroup_root *root, u64 id);

#else /* !CONFIG_CGROUPS */



struct cgroup_subsys_state;

kernel/cgroup/cgroup.c

+39 −2
Original line number Diff line number Diff line
@@ -475,7 +475,7 @@ static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, 
 * Find and get @cgrp's css assocaited with @ss.  If the css doesn't exist

 * or is offline, %NULL is returned.

 */

static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,

struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,

					      struct cgroup_subsys *ss)

{

	struct cgroup_subsys_state *css;
@@ -6080,6 +6080,43 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, 
	return retval;

}



struct cgroup *cgroup1_get_from_id(struct cgroup_root *root, u64 id)

{

	struct kernfs_node *kn;

	struct cgroup *cgrp, *root_cgrp;



	kn = kernfs_find_and_get_node_by_id(root->kf_root, id);

	if (!kn)

		return ERR_PTR(-ENOENT);



	if (kernfs_type(kn) != KERNFS_DIR) {

		kernfs_put(kn);

		return ERR_PTR(-ENOENT);

	}



	rcu_read_lock();



	cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);

	if (cgrp && !cgroup_tryget(cgrp))

		cgrp = NULL;



	rcu_read_unlock();

	kernfs_put(kn);



	if (!cgrp)

		return ERR_PTR(-ENOENT);



	spin_lock_irq(&css_set_lock);

	root_cgrp = current_cgns_cgroup_from_root(root);

	spin_unlock_irq(&css_set_lock);

	if (!cgroup_is_descendant(cgrp, root_cgrp)) {

		cgroup_put(cgrp);

		return ERR_PTR(-ENOENT);

	}



	return cgrp;

}



/**

 * cgroup_fork - initialize cgroup related fields during copy_process()

 * @child: pointer to task_struct of forking parent process.